Question

Determine the charge that produces an electric field strength of 40 V/cm at a distance of 30cm in vacuum(in 10^-8C)

(a) 4

(b) 2

(c) 8

(d) 6

This question was addressed to me in a national level competition.

The question is from Electric Field Intensity in chapter Electrostatic Fields of Electromagnetic Theory

Answer 1

The correct choice is (a) 4

Explanation: E = Q/ (4∏εor^2)

Q = (4000 X 0.3^2)/ (9 X 10^9) = 4 X 10^-8 C.